文件名称：Voice Over IP Tutorial
文件大小：231KB
文件格式：PDF
更新时间：2013-09-30 17:36:59
VoIP
Telephone companies offload voice calls from public switched telephone networks (PSTNs) to voice-over-Internet Protocol (VoIP) networks because it is cheaper to carry voice traffic over Internet Protocol (IP) networks than over switched circuit networks. In the future, IP telephony networks are expected to enable innovative new multimedia services while working seamlessly with legacy telephone networks.